Assessment of Soil Organic Matter Depletion in Intensively Farmed Areas of Ekiti State, South West Nigeria

This study assesses the degree of soil organic matter depletion in intensively farmed communities of Ekiti State, located in Nigeria's South West geopolitical zone. Soil organic matter depletion is a leading indicator of soil health decline, affecting nutrient cycling, water retention, and biological diversity, and has been accelerated in Ekiti State by high population pressure on agricultural land, vegetation clearance, and limited organic matter recycling by farmers. Surface soil samples were collected from 40 farms across Ekiti Central, Ekiti South West, and Ado-Ekiti local government areas, together with five reference forest sites. Organic carbon was determined by Walkley-Black, total nitrogen by Kjeldahl, and the carbon-to-nitrogen ratio was calculated. Humic acid and fulvic acid fractions were extracted by NaOH fractionation to characterise organic matter quality. Farmer management practices were documented by structured interview. Findings revealed that 80 percent of farmed soils had organic carbon below 1.5 percent, compared to mean forest soil organic carbon of 4.1 percent, representing a 63 percent average depletion. The carbon-to-nitrogen ratio was narrow (less than 12) in the most depleted soils, reflecting predominance of mineralised, labile organic fractions with low humus content. Farms practising crop residue burning and no manure additions showed the greatest depletion. The study recommends integration of organic amendments, promotion of green manure crops, and extension campaigns on organic matter conservation as priority interventions for Ekiti State soil health restoration. Keywords: soil organic matter depletion, intensive farming, Ekiti State, humic substances, soil health.